Keyboard interlock for calculating



Ot. 2, 1951 I F, NlEMANN 2,570,068

KEYBOARD INTERLOCK FOR CALCULATING MACHINES I I Y @Q00@00000 up 000000000 11? 0. 0000000001 gq p 1 0000 00000 u p 0000000005 q P 000000000 QP 000000000 11? L000000000 2n? Oct. 2, 1951 F. A. NIEMANN 2,570,068

A KEYBOARD INTERLOCK FOR CALCULATING MACHINES I Filed June 15, 1945 12 Sheets-Sheet 2 Oct. 2, 1951 A, NiEMANN 2,570,068

KEYBOARD INTERLOCK FOR CALCULATING MACHINES Filed June 15, 1945 12 Sheets-Sheet 5 1951; F. A. NIEMANN 2,570,068

KEYBOARD INTERLOCK FOR CALCULATING MACHINES Filed June 15, 1945 12 Sheets-Sheet 4 Oct. 2, 1951 F. A. NIEMANN 2,570,068

KEYBOARD INTERLOCK FOR CALCULATING MACHINES Filed June 15, 1945 12 Sheets-Sheet 5 12 Sheets-Sheet 6 44 Mehibr Oct. 2, 1951 F. A. NIEMANN KEYBOARD INTERLOCK FOR CALCULATING MACHINES Filed June 15, 1945 Oct. 2, 1951 F. A. NIEMANN KEYBOARD INTERLOCK FOR CALCULATING MACHINES Filed June 15, 1945 12 Sheets-Sheet '7 F wmmw Oct. 2, 1951 F. A. NIEMANN KEYBOARD INTERLOCK FOR CALCULATING MACHINES Filed June 15, 1945 12 Sheets-Sheet 8 wdeiz c'kai.

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Oct. 2, 1951 F. A. NIEMANN KEYBOARD INTERLOCK FOR CALCULATING MACHINES 12 Sheets-Sheet 9 Filed June 15, 1945 Oct. 2, 1951 F. A. NIEMANN KEYBOARD INTERLOCK FOR CALCULATING MACHINES 12 Sheets-Sheet 10 Filed June 15, 1945 Oct. 2, 1951 F. A. NIEMANN KEYBOARD INTERLOCK FOR CALCULATING MACHINES Filed June 15, 1945 12 Sheets-Sheet 11 Oct. 2, 1951 F, N|EMANN 2,570,068

KEYBOARD INTERLOCK FOR CALCULATING MACHINES Filed June 15, 1945 12 sheets-sheet 12 latented Oct. 2, 1951 KEYBOARD INTERLOCK FOR CALCULATING MACHINES Frederick A. Niemann, Chicago, Ill., assignor to Felt & Tarrant Manufacturing Company, Chicago, 111., a corporation of Illinois Application June 15, 1945, Serial No. 599,561

14 Claims.

This invention relates in general to calculating machines, and more particularly to error preventing mechanism for key-driven calculating machines, such as the well-known duplex Comptometer.

Such key-driven calculating machines are especially well adapted for rapid operation in all types of calculation; maximum speed being attained by a trained operator in addition and subtraction by employing only the first five ordinal keys (l-5) in the various denominations, and in multiplication and division by actuating a key in each desired denominational order simultaneously using a different finger for each order and both hands if necessary.

Error control mechanism has been provided in the prior art for preventing mismanipulation due to partial key strokes, such as that disclosed in United States Letters Patent No. 1,818,425 granted August 11, 1931, to Frederick A. Niemann, which retains a partially depressed key in a partially depressed position and locks all other keys of the machine against actuation, while permitting correction of the error by complete depression of the partially operated key, which alsois then looked against actuation upon its return to normal position. The mechanism provided by the prior art, however, has certain disadvantages; for example, a plurality of keys in any one denominational order can be partially depressed; if only one is corrected, the others partially depressed also are restored to elevated position but without correction. Another disadvantage of the prior art mechanism is that regardless of the extent of partial depression of any ordinal key, that key is retained only in a very slightly partially depressed position, thereby offering a relatively poor visual indication of which key was partially depressed and requires corrective actuation.

A principal object of the instant invention is the provision in a calculating machine of improved error preventing mechanism operable differently during difierent types of calculation to obviate and prevent mismanipulation due to partial depression of ordinal keys in the manner best suited to the particular method of machine calculations being employed.

Another important object of the invention is the provision of novel means for releasably latching any ordinal key to its associated actuating mechanism throughout the active phase of a complete operation of said key.

Another important object of the invention is the provision of means for retaining any ordinal 2 key or keys which have been partially depressed, in such partially depressed position, substantially equal in depressive extent to the degree of-partial actuation imparted thereto, so as to offer a distinct and instantly recognizable visual indication of which key or keys require corrective actuation.

A further important object is the provision of such mechanism which also prevents depression of more than one key at a time in each denominational order and locks the entire keyboard against actuation upon partial depression of any ordinal key or keys, except the key or keys partially depressed, which are retained in that position.

Another object of the invention is to provide means particularly useful during the performance of addition or subtraction to effect locking of any partially depressed key upon its return to normal position following corrective complete depression thereof, and control mechanism manually operable to release for actuation the entire keyboard thus locked.

A further important object of the invention is the provision of an error correction control, particularly useful during the performance of multiplication or division, which is selectively operable to render ineffective the above referred to means for locking partially depressed keys following corrective actuation thereof, whereby complete depression of all keys partially depressed causes immediate automatic unlocking of the entire keyboard.

Another object is to provide error correction means for positively assuring that complete corrective depression is imparted to all partially depressed ordinal keys.

A further object of the invention is the provision of yieldable means associated with the means for retaining ordinal keys in partially depressed positions which will prevent injuring the mechanism by any attempts to force partially depressed keys upwardly.

Numerous other objects and advantages of the invention will be apparent as it is better understood from the following description which, when taken in connection with the accompanying drawings, discloses a preferred embodiment thereof.

In the drawings:

Fig. 1 is a plan view of a calculating machine of the multiple order, key-driven type in which the present invention is embodied;

Fig. 2 is a side elevational view of the front portion of the machine, as seen from the left of kJ Fig. 1, with part or the side wall of the casing removed;

Fig. 3 is a side elevation, viewed from the left of Fig. 1, with part of the casing removed and the front portion of the machine and some other mechanism omitted, showing the mechanism associated with one denominational order in normal or inoperative position;

Fig. 4 is a view similar to Fig. 3 showing one of the digital keys (the 8 key) at that point of initial depression just prior to forward movement being imparted thereby to the associated auxiliary key lock lever;

Fig. 5 is a view similar to Figs. 3 and 4 showing a digital key in a partially depressed position;

Fig. 6 is a view similar to Figs. 3 to 5, showing a digital key, which has been partially depressed and released, locked in partially depressed position;

Fig. 7 is a view similar to Figs. 3 to 6, with the additional disclosure of the ordinal gang key locking mechanism, and showing the previously illustrated, partially depressed, digital key in fully depressed position;

Fig. 8 is a detail view of part of the ordinal mechanism showing the position assumed thereby during return movement of a digital key which has been fully depressed;

Fig. 9 is an enlarged detail view similar to Fig. 3;

Fig. 10 is an enlarged detail view similar to Fig. 5;

Fig. 11 is an enlarged detail view similar to Fig. 6;

Fig. 12 is an enlarged detail view similar to Fig. 7;

Fig. 13 is an enlarged detail plan view, similar to Fig. l, of part of the left-hand portion of the machine, with some of the casing removed and part or" the mechanism of th highest denominational order in horizontal section;

Fig. 14 is a detail perspective of part of the mechanism of Fig. 8;

Fig. 15 is a, detail perspective or an ordinal key lock lever actuator;

Figs. 16 and 17 are detail vertical cross sections on lines l6l6 and Il-IT, respectively, of Fig. 3;

Fig. 18 is a detail side elevation, similar to Fig. 3, showing the error correction mechanism in active position;

Fig. 19 is a view similar to Fig. 13 of part of the error correction mechanism in active, actuated position;

Fig. 20 is a detail view similar to Fig. 18 of the error correction key mechanism in inactive position; and

Figs. 21, 22 and 23 are detail perspective views of some of the latch levers of the error control mechanism.

The general construction of the Comptometer herein illustrated is described in the following Letters Patent of the United States: Dorr E. Felt, No. 762,520 and No. 762,521, granted June 29, 1904; No. 1,028,344, granted June 4, 1912; No. 1,066,096, granted July 1, 1913; No. 1,072,933, granted September 9, 1913; Kurt F. Ziehm, No. 1,110,734, granted September 15, 1941; Joseph A. V. Turck, No. 1,357,747 and No. 1,357,748,

granted November 2, 1920, and No. 1,449,639,

granted March 27, 1923, and Frederick A. Nieinann, No. 1,818,425, granted August 11, 1931.

Since the details of construction and operation of the instant calculating machine are described in the above-listed Letters Patent of the 4 United States, a brief description of the general features or" this machine will be sufficient for an understanding of this invention.

The various parts and mechanisms of the illustrative machine are supported by skeleton framework mounted on the base plate of a casing 2i. This framework includes side skeleton plates 22 (Figs. 2 and 13) and intermediate skeleton plates 23 located respectively at the right and left sides of the machine and between the several orders thereof. These plates 22 and 23 are tied together by a number of transverse tie rods 24 (Figs. 2, 7, and 13), providing a rigid construc tion on which are mounted the movable parts of the machine.

A number of duplicate orders each having nine (9) digital keys 25 is provided, and each order or column of keys is coordinated with a registering or numeral wheel, by means of interposed actuating and accumulator mechanisms and other parts. The keys 25' of each order are adapted to induce the operation of the corresponding actuating mechanism which transmits to an accumulator mechanism, including the registering wheels, and amount of travel determined by and proportioned to the numerical value of the particular key operated.

The actuating mechanism of each order includes a column actuator 26, in the form of a segment lever pivoted at the rear end of the machine and adapted to be depressed varying distances, determined by any particular key 25 of that order struck by the operator. The keys are provided with stems 2! which extend down and bear upon the corresponding column actuator 28, for the purpose of transmitting thereto movement induced by depressing the keys.

The key at the extreme front of the machine, being further from the axis of the column actuator than the key at the extreme rear of the machine, moves the column actuator a shorter distance ian does the rear key last mentioned. The keys of each column are numbered from 1 to 9 from the front to the rear of the machine. The 1 key at the extreme front moves the column actuator a distanc substantially oneninth of that effected by the operation of the 9 key at the extreme rear of the machine. Upon depression of intermediatel positioned keys, the column actuator is operated distances respectively proportioned to the value of the intermediate key operated.

Each column actuator 26, when operated, imparts calculating movement to its corresponding accumulator mechanism, and, for this purpose, is provided at its forward end with a rack 28 (Fig. 2) which meshes with an accumulator pinion 29 journaled on a transverse shaft 30 extending across the machine and supported in the framework. The pinion 29 of each order is coordinated with an internal ratchet mechanism, not herein described, but fully set forth in certain of the United States patents hereinbefore mentioned (see particularly Patents Nos. 762,520, 762,521, 1,028,344, 1,066,096, 1,072,933, and 1,110,734).

It will be sufficient to state that the ratchet mechanism is interposed between the pinion 29 and the lantern wheel 3| and becomes effective on the up-stroke of the column actuator to clutch the pinion 29 to the lantern wheel 3|, which normally is connected operatively by a gear train 33 (Fig. 2) with the numeral wheel pinion 36. The numeral wheel pinion 36 is journaled on the transverse shaft 37 and is secured to its corresponding numeral or registering wheel 38. During the downward movement of a column actuator 26, the internal ratchet mechanism moves idly with respect to the lantern wheel 3|, so that the gear train 33 and the numeral wheel pinion 36 remain stationary. However, during the return or up-stroke of the column actuator, the clutching of the accumulator pinion 29 to the lantern wheel 3|, by said internal ratchet mechanism, operates the interposed gear train 33, so that the numeral wheel 38 is rotated a distance determined by the particular key of its corresponding order that has been first depressed and next released. Whenever an actuated key is released at the end of a full downward stroke, the column actuator is moved upwardly by the column actuator springs 39 (Figs. 3 and 13).

Carrying mechanism is cooperatively combined with each ordinal accumulator mechanism for the purpose of actuating the accumulator mechanism of the next higher order of the machine whenever a carry is to go over from a lower order. This carrying mechanism is illustrated in detail in Patents No.1,357,747 and No. 1,357,748, and described in a general manner in Patent No. 1,818,425.

Those patents also specifically illustrate and describe zeroizing or canceling mechanism for returning the register wheels and other parts to normal or inoperative position.

Means are provided for relieving the digital keys of the necessity of stopping the respectively associated column actuators in their downward movement and for insuring accurate extent of movement thereof comprising in each order of the machine even and odd key stop levers and 5|, best illustrated in Figs. 7 and 17, which are mounted for pivotal movement at the rear of the machine upon a transverse rod 52. One of each of such key step levers 50 and 5| is associated with each column or order of the digital keys 25. In the final portion of the downward movement of any of the digital keys 25, a laterally extending shoulder 53 on the stem 21 thereof imparts a slight degree of downward movement to its associated key stop lever 50 or 5|, depending upon whether such key is of even or odd digital value. This downward pivotal movement of the key stop lever swings an associated even or odd actuator stop lever 54 or 55 in a counter-clockwise direction, viewed in Figs. 7 and '12, to carry a suitable stop lug 56 (Fig. 7) on the depending end thereof forwardly into engagement with the proper one of a series of teeth 51 provided on the rear edge of the rack end 28 of the column actuator 26. The specific construction and detailed operation of this particular stop mechanism is fully illustrated and described in Patent No. 762,520.

Means are provided for, among other functions, preventing actuation of the accumulator during downward pivotal movement of the column actuator 26. In each denominational order of the machine an auxiliary key lock lever 86, provided at its rear end with an elongated aperture 84, is by means of that aperture pivotally and reciprocably mounted on a cross rod which is suitably supported at the rear of the machine and which forms the pivot for all of the column actuators 26. Each auxiliary key lock lever 85 is provided with upstanding shoulders or projections 81 adapted, upon initial depression of any one of the associated digital keys 25, to be contacted by a lateral projection 58 (Fig. 17) formed on each of the key stems 21. The lever 86 is further provided with a roller 88 which rests on the horizontal forwardly extending arm 89 of an elbow lever 90 pivoted at 9I on the column actuator 26. The elbow lever has an inner vertical arm 92 (Fig. 13) which is connected by a spring 93 to the associated column actuator 28, so that the elbow lever is normally pulled back into vertical position with its horizontal arm bearing up against the roller 88 of the key lock lever 86. The elbow lever 90 also has an outer vertical arm 94 pivotally connected with a forwardly extending link 95. This pivotal connection is of the pin and slot type which permits a slight forward and rearward relative movement between the arm 94 and the link 95, the latter normally being retained in its forwardmost position of Fig. 3 by a spring 95 extending between the uppermost ends of these two parts.

Each link 95 is connected by a pivot 91 at its forward end to a swinging link 98 pivotally mounted in the frame of the machine at 99 and having a forwardly extending arm I00 adapted to limit counterclockwise movement thereof, as viewed from the left of the machine, by contact with a cross rod WI.

The pivot 91 carries in each denominational order a forwardly and backwardly and upwardly and downwardly movable lever I03, the forward arm of which is urged upwardly by a spring I05 connected at its upper end to the cross rod IOI. The forward end of each lever I03 is provided with a pin I96 which engages a slotted arm I0! of an accumulator locking detent lever I08, there being one such lever I08 pivoted in each denominational order on a cross rod I09. With this arrangement, the forward arm of the lever I03 and the arm I07 of the detent lever, during upward and downward movement thereof, will respectively engage and disengage the forward depending endof the detent with and from the lantern wheel 3| of the associated accumulator mechanism. When the said detent engages the said lantern wheel, it and its accumulator mechanism are locked against rotation, and it is necessary to remove the detent when and as the downward movement of the column actuator 26 is completed to permit the actuator to impart movement to the accumulator during its return stroke.

The major portion of this mechanism is dis- 5 closed in greater detail in Patent No. 1,110,734.

In the final portion of the downward movement of any of the digital keys 25, the resulting actuation of the associated key stop lever 50 or 5| and actuator stop lever 54 or 55 causes one or the other of the latter to depress the forward end of the lever I03, by means of laterally projecting lugs 59 or 60 (Fig. 12) formed respectively on the rearwardly extending arms thereof, to disengage the locking detent lever I08 from its accumulator.

Error control mechanism is provided for locking the various denominational orders of the accumulator, actuating mechanism, and the digital key or keys depressed to effectuate an actuation thereof, whenever one or more of such keys is released prior to completion of full downward stroke thereof. Since the error control mechanism, except as hereinafter indicated, is duplicated in the various denominational orders, only one such order thereof will be herein disclosed in detail.

The error control mechanism prevents mismanipulation of the above-described mechanism due to partial key strokes, retaining a digital key which has been partially depressed in such partially depressed position, substantially equal in depressive extent to the degree of partial actuation imparted thereto, so as to offer a distinct and instantly recognizable visual indication of which key or keys require corrective actuation. Each of the levers I93 is provided to the rear and adjacent its pivot 9'! with a lateral extension or shelf 5 i I (Figs. 9 and 14) which normally rest at its free end on the upper surface of a vertical extension H2 formed on the associated column actuator 25 to limit counter-clockwise movement of the lever 193, as viewed from the left of the machine, b the spring I95. Thus forward movement of the link 95 caused by initial depression of any digit key 25 from its position of Fig. 3 to the partially depressed position of Fig. 4, in the manner hereinbefore described, is accompanied by forward horizontal movement of the lever I03, with the shelf II I riding on the extension H2 and being held thereon by the spring I05. Such forward movement of the lever I03 is limited by contact of the arm I of the swinging link 98 with the cross rod IOI.

At this point in the depression of any digital key 25, the projection on its key stem 2": comes into contact with the associated column actuator 26, and further depression of the key, as from the position of the depressed key of Fig. 4 to that of Fig. 5, results in downward swinging of the column actuator to disengage the projection IE2 from the shelf I II and permit the spring I05 to swing the lever I03 about its now stationary pivot 97 to raise its forward end carrying the pin I06 and throw the detent lever I88 into locking engagement with the associated accumulator mechanism. The lever E03 thus assumes its position of Figs. 5 and 10, in which the nose [I3 at its rear end, normally extending above a square shaft or bail iii as seen in Figs. 3 and 9, is now disposed in horizontal alignment with and forwardly of the bail H 2. The bail H4- extends laterally across the machine and is supported by arms I45 from a rock bar I I6, a spring ii? (Fig. connected between an arm H5 and a punched out lug on a side frame member of the machine, urging pivotal movement of the arms I I5 and bail E I in a counter-clockwise direction, as viewed from the left of the machine. Movement to front or rear of the bail H4, however, is limited by a cross shaft H8 extending through apertures in the arms H5.

Release a digital key at any partially depressed position, as in Figs. 5 and 10, will result in the usual spring at the bottom of its stem attempting to move it upwardly, and the actuator springs 39 atte rating to return the column actuator 2a to normal position. The latter is prevented, hcwerer, by the accumulator locking detent lever I88 which is in engagement with the lantern wheel 3i. Consequently, the only movement of the parts which is permitted upon release of a partially depressed key is a sli ht raising of the auxiliary key lock lever by the spring as and elbow lever from the position of Figs. 5 and 10 to hat of 6 and i1. Ihis is accompanied, through the agenc of the link 95, by a horizontal rearward movement of the lever I03 which is terminated by the nose IE3 abutting against and swinging the bail I I4 rearwardly fill until the forward surfaces of the recesses H9 in the arms H5 contact the cross rod II8. Such movement of the parts is insufficient to disengage the associated tooth I52 on the lever 80 from the recess I5I in the key stem 21 (such parts to be hereinafter described in detail), and since this movement is limited in the manner above described, the partially depressed and released digital key 25 thus is locked in partially depressed position.

Means are provided for retaining the bail H4 in its actuated or rearmost position of Figs, 6 and 11 until corrective actuation of the mismanipulated key or keys have been affected by completely depressing the same. This means comprises in each denominational order a latch lever I2I (Fig. 21) pivotally mounted on a cross shaft I22 at its forward end and terminating at its rear end in a notched portion I23 (Fig. 14). Intermediate its ends the latch lever I2I is provided with 2. laterally projecting shelf I24 overlying and normally held in engagement with a vertical projection I25 on the lever I03 by a spring I26, in the position shown in Fig. 9. Depression of any digital key results in downward movement of the rear end of the lever I03 to its position of Figs. 5 and 10, as above described, which permits the spring I26 to pull the rear end of the latch lever I2l into contact with the top surface of the bail H4, or into active position. Rearward movement of the bail IE4 by the lever I33 when a partially depressed key is released, in the manner described, permits the spring I26 to swing the rear end I23 of the lever I2I down into latching engagement with the bail I M, as shown in Figs. 6 and 11, where it is retained until complete depression of the mismanipulated key raises the rear end of lever I03 to cause projection I25 to strike the shelf I24 and lift the latch lever out of engagement with the bail.

Corrective actuation of the mismanipulated key or keys, comprising complete depression thereof, raises the rear end of the associated lever I03 to its position of Figs. 7 and 12 by virtue of the associated even or odd key stop lever or 5| actuating its actuator stop lever 54 or 55 to cause the lug 59 or 60 thereon to depress the forward end of the lever I03. This also swings the accumulator locking detent I08 out of engagement with the accumulator, in well-known manner, to permit the column actuator 23 to impart additive actuation to the accumulator upon its subsequent upward movement.

Means are provided for retaining the lever I03 with its rear end raised (as shown in Fig. 8) throughout the return additive movement of the column actuator to prevent re-engagement of the lever with the bail H4 and rte-engagement of the detent I08 with the accumulator until completion of the upward key stroke. The lever I03 is provided with an upwardly extending arm I21 (Fig. 14) having a lateral projection thereon adapted to cooperate with the upper arm I28 of a latch lever I28, I29 (Fig. 22) pivoted on the cross rod II8; the lower arm I29 normally being engaged by a projection I3I on the column actuator 26, as seen in Fig. 9. A third arm I32 of the latch lever I28, I29 is connected to a spring I33 anchored to a cross shaft I34. Downward movement of the actuator by a digital ke releases the lever I28, I29 for active cooperation with the lever I03. At the completion of a key stroke, the resulting downward movement of the forward end of lever I03 from its position of Figs. 6 and 11 to that of Figs. 7 and 12 rocks the arm I21 forward to permit the arm I28 to be latched behind the lateral projection thereon by the spring i33. Upon return of the column actuator 26 to normal position, the projection I3I thereon disengages the latch lever I28, 29 from the lever I63 to permit the latter to be moved horizontally to the rear by the spring 8-3. There is a further means for insuring the lever I03 being retained in its position of Fig. 8 during return movement of the column actuator by preventing said lever from tilting during this phase of the operation. This means comprises a latch I35 (Fig. 23) which hooks under the lateral projection on a depending arm I36 on the lever I63 under the influence of a spring I31, when the parts move from their positions of Figs. 6 and 11. to those of Figs. 7 and 12 upon completion of a downward digital key stroke. The latch I35 is pivoted on the cross rod II 8, the spring I31 being connected between the upper portion of the latch and a punched out lug on the adjacent machine frame member, and a rearwardly extending arm I 38 of latch I35 rests upon cross shaft I22 to limit movement of the latch by the spring I31. These parts fall from their positions of Figs. 7 and 12 to those of Fig. 8 immediately upon release of downward pressure on the digital key after complete depression thereof. As the column actuator 26 arrives at its highest point, the projection I 3I disengages the latch I23, I23 from the arm I21 of the lever I63 to permit the latter to be moved horizontally to the rear. During the major portion of such movement, and until such time as the rear nose H3 of the lever I63 is over the bail IN, the lateral projection of the arm I36 rides upon the hook portion of the latch l3'5, falling below the latter as it slides off of it so as to prevent re-engagement upon subsequent down-strokes of any of the digit keys of the same denominational order.

The stem 21 of each of the digital keys 25 is provided adjacent the projection 38 thereon with a forwardly extending recess I 5| (Figs. 12 and 17) adapted to cooperate with a forwardly extending lug or tooth I52 formed on the upper edge of the associated auxiliary key lock lever 86. As Will. be seen from the drawings, each lever 86 is provided with a plurality of such teeth I52 disposed respectively just to the rear and adjacent each of the associated key stems 21.

Means are provided for moving the auxiliary key lock lever 86 forwardly to engage one of the teeth I52 in the recess I5I of the-stem 21 of any digital key 25 upon downward movement of the latter, whereby to lock the depressed key to the column actuator 26 throughout substantially a complete or full key stroke downwardly from and upwardly to the position at which the laterally extending lug 53 on the key stem engages and disengages the column actuator 26. In each denominational order of the machine this means comprises a depending key lock lever ac tuating lever I 53 (shown in perspective in Fig. 15) pivotally mounted at its upper end on a cross rod I54. At its lower end, lever I53 is pivotally connected at I55 to a rearwardly extending link l56. The rear end of the link I55 is provided with. a slot I51 (Fig. 3) slidably engaging a pin 558 carried by the associated auxil iary key lock lever A spring I56 connected at its rear end to the pin I58 is attached at its forward end to a laterally extending ear I56 of the link I56. The specific purpose of this yieldable connection between the link I56 and its as- 10 sociated key lock lever 86 will be described hereinafter.

Adjacent its lower end, the actuating lever I53 is provided with a cam roller I BI and a recess I62, the latter normally engaging a roller I63 mounted on the associated column actuator 26.

Referring now particularly to Figs. 3 to 7 and 9 to 12 of the drawings, initial depression of any one of the digital keys 25 from the normal position of Figs. 1 and 9 to the position illustrated in Fig. 4 results in the lug 58 on the stem 21 thereof swinging the auxiliary key lock lever 86 downwardly relative to the column actuator 26 to move the lever I 63 forwardly in the manner hereinbefore described. At this point in the downward movement of the key, the lug 58 comes into contact with the upper edge of the column actuator 26. Continued downward movement of the digital key, causing downward swinging movement of the column actuator 26, results in the roller I53 mounted on the latter acting upon the roller I6I to swing the lever I53 forwardly and, through the agency of the link I56 and spring 59, to move the auxiliary key lock lever 86 forwardly from its position of Figs. 3, 4, and 9 into its position of Figs. 5 to 7 and 10 to 12, such movement being permitted by the elongated aperture 84. This forward movement of the levor 36, best seen in Figs. 10 to 12, causes the associated tooth I52 thereon to engage within the recess I5I in the stem of the depressed key. The roller l6-3' thereafter, during the remainder of the down stroke of the key and the initial portion of its up stroke, cooperates with a rear cam surface I53 (Figs. 10, 15 and 16) of the lever I53 to hold the tooth 152 in the recess I 5| of the depressed key stem. Following complete depression of the digital key 25, the active return movement of the column actuator 26 by its springs 39 causes the roller I63 to reenter the cam recess I62 to return the actuating lever I53 and auxiliary key lock lever 86 to their normal inactive positions, such action taking place during the final increment of return movement of the column actuator. The actuated key is thus retained in locking engagement with the lever 86 throughout both downward and upward movement from its initial point of depression, as illustrated in Fig. 4, back to such position in its return to normal.

The previously described operation of the error control mechanism to prevent return movement of the lever 86 upon partial depression and release of a digital key 25 thus functions to retain such partially depressed key in partially depressed position, instead of permitting its return to an initial partially depressed position in the manner of the prior art.

During the time that any digital key 25 is in partially depressed position, means are provided for preventing actuation of any of the other digital keys of the same denominational order. This means comprises a gang or series of key locks 565, Fig. 7, pivotally mounted at I65, respectively, between each adjacent pair of key stems 21. These locks I64 are substantially U- shaped, and have each of their depending arms provided with extensions I66 adapted to engage against shouldered recesses I61 provided in one edge of each of the key stems 21 (Figs. 7 and 1'1). The locks I64 are so disposed that adjacent extensions I66 thereof are normally substantially in contact with each other in the recesses I61 of the associated key stems 21, there being an aggregate or total spacing longitudinally of the machine between all adjacent extensions I66 of each ordinal series of key locks I64 equal only to the thickness of one of the key stems 21, so that depression of any key 25 of any particular de nominational order will swing the adjacent locks away from the stem of the actuated key, the latter blocking return movement of each of said adjacent locks until said depressed key returns to normal elevated position. Thus, during the time that any key is in a partially depressed position, one of the extensions I88 of each of the locks I64 is engaged in the shouldered recess IS! of each of the other keys in that denominational order to prevent operation thereof.

Means are also provided for looking all of the column actuators against operation whenever any digital key is partially depressed and released, except the column actuator of that denominational order in which a key has been so mismanipulated, to prevent actuation of all of the other keys of the machine until corrective actuation of the mismanipulated key has been made. Pivotally mounted on the cross shaft I34 in each denominational order of the machine is a looking pawl or hook Ill. The lower portion of the pawl I'II is normally out of, and adapted to swing forwardly into, engagement with an upstanding hook I12 provided on the column actuator 28, as illustrated in Fig. 9. The upper end of the pawl I'lI is provided with a forward extension or arm I13. A bell crank lever I14 is pivotally mounted on the cross shaft I34 in cooperative association with the pawl ill, with one arm thereof engaging against the upper surface of a cross rod I15 carried by the arms IE5, and the lower arm thereof connected by a spring IE8 to the depending portion of the pawl Ill. The spring I16 thus functions to retain the forwardly extending arm I13 of the pawl I'll against the under surface of the cross rod I15.

Upon clockwise movement of the bail H4 and arms I I as hereinbefore described, from the position of Figs. 9 and to the position of Fig. 11, due to partial depression and release of a digital key, the cross rod H5 is moved upwardly to swing all of the pawls I'II in acounter-clockwise direction. Such movement of the pawls IlI moves the depending arms thereof forwardly to cause their engagement with the associated hooks In to prevent downward movement of the column actuators 26 in all denominational orders of the machine other than that of the mismanipulated key. At this time, accumulator locking detent lever I88 in that denominational order in which a key has been mismanipulated is functioning as above described to prevent upward or return movement of its associated column actuator. Upon complete depression of the mismanipulated key, return of the bail H4 and arms II5 to normal position in the manner hereinbefore described will be accompanied by downward movement of the cross rod I75 to return all of the pawls I'lI to normal or inoperative position.

Means are provided, particularly useful dur ing the performance of addition or subtraction, to prevent such return of the locking pawls I?! to normal position upon corrective actuation of a mismanipulated key so as to effect complete locking up of the entire machine, including the mechanism of that denominational order in which an error in key depression has been made and corrected. This means comprises mechanism mounted to the left of the highest denominational order of the machine for selective active association with the rockable cross rod or bail II4 carried by the arms II5, as best illustrated in Figs. 18 and 19. Pivotally mounted on a shaft I8I at the left-hand side of the machine is a latch lever I82, the rear end of which normally rests upon the upper surface of the bail II4 (as shown in Fig. 18) and is provided with a retaining notch I83. A spring I84 connected at its upper end to a cross rod I85 is connected at its lower end to the latch lever I82 forwardly of its pivot I8I to urge and yieldably retain the latch lever in engagement with the bail II4. When the error control mechanism is rendered operative in the manner hereinbefore described, causing the bail II4 to be swung rearwardly from its position of Fig. 18 to its position of Fig. 19, the latch lever I 82 is swung into the operative position of the Fig. 19 by the spring I84. Consequently, subsequent corrective actuation of the key or keys which have been mismanipulated, while causing the remainder of the error control mechanism to be returned to normal position as previously described, nevertheless results in complete locking of the machine by virtue of the action of the latch lever I82 retaining the bail I I4, and consequently the locking pawls Ill, in active position. The spring I'IB of the locking bail assembly I'II in that denominational order in which corrective actuation has been applied to a mismanipulated digital key permits the hook Il2 on the column actuator 26 of that order to swing the pawl III rearwardly as it rises to normal position and then functions to return said bail forwardly into active locking engagement with that hook I12.

Control mechanism is provided which is manually operable to release for actuation the entire keyboard thus locked. This mechanism comprises an error release key I88 centrally located at the forward end of the machine (Figs. 1 and 2) which is connected to the forward end of a laterally and rearwardly extending lever I81 in the form of a rod pivotally mounted in a suitable bearing at I88 (Figs. 2 and 18) and extending downwardly and rearwardly from such pivot point. The rearward terminal end of the rod I8'l abuts against a suitable pad provided on the depending end of a bell crank lever I89 which is pivoted intermediate its ends on the cross shaft I35. Spring I98 holds the depending end of the lever I89 in yielding engagement with the rear end of the rod I87. Following movement of the latch lever I82 into its active position of Fig. 19 by the spring I84, release thereof may be effected by downward movement of the error release key I86, resulting in raising of the rear end of the rod I81 to swing the lever I89 in a clockwise di rection, as viewed from the left side of the machine, to lift the latch lever I82 out of engagement with the bail II4 to permit the arms H5 and the locking bails ill to be returned by the spring I IT to normal or inoperative position.

Means are also provided for accomplishing this same result of releasing for actuation the entire keyboard following locking thereof due to mismanipulation of a digital key and subsequent corrective actuation thereof whenever the canceling mechanism is operated to zeroize the accumulator. As is well known, and specifically illustrated in Patent No. 1,357,747, zeroizing of the accumulator in this type of machine is accom plished by detraining the gears 32 from the gearing of the lantern wheel shaft 38 to release the carrying springs M to permit them to turn the several registering wheels rearwardly from their various positions to normal or zero position. To effectuate such action, a zeroizing handle or canceling crank ll is provided (Fig. 18) which is pivoted adjacent its lower end and swung forwardlly, or clockwise viewed in Fig. 18, for zeroizing, and is connected by a link '53 to a dependin lever I4 that is pivoted at its upper end by being rigidly mounted on a rock shaft l5 rotatably mounted on the frame of the machine. The lower end of the lever I4 is pivotally connected by means of a link 16 with an arm I? rotatably mounted with respect to a transverse shaft I8 that is journalled on the frame of the machine. The arm 7! is provided with an engaging face I9 adapted to contact with a second arm 89 fixed on the shaft I8. Forward swinging movement of the canceling crank II (clockwise in Fig. 18) thus imparts a short rocking movement to the shaft I8 to swing the frame carrying the gears 32 forwardly to detrain the same from the gearing of the lantern wheel 39 and also to impart a slight counter-clockwise rotation to the rock shaft I5, all as described in said Patent No. 1,357,747.

The rock shaft I5 has rearwardly extending arms 8| secured thereto in each denominational order of the machine for cooperation during zeroizing with the rear ends of the locking detent levers I98 (Fig. 2) as described in the prior listed patents and particularly No. 1,357,747, and one such arm adjacent the left end thereof which extends rearwardly over the forward end of the bell crank lever I99 (Fig. 18). Zeroizing of the accumulator thus results in clockwise movement of the bell crank lever I 89, as viewed in Figs. 18 and 19, to release the latch lever I82 from engagement with the bail H4 in the manner above described.

Error correction control means, particularly useful during the performance of multiplication and division, is selectively operable to render ineffective the above described means for locking partially depressed keys following corrective actuation thereof. For that purpose an error correction control key I96, as shown best in Figs. 1, 18, and 20, is mounted at the left side of the machine. Intermediate its ends, the stem of the error correction control key I95 is connected by a pin and slot connection I95 to the rear end of a forwardly extending link I9I. The forward end of that link I9! is provided with a slot I9I slidably engaging a reduced portion of the rock shaft I5 and is connected by a spring I98 to an intermediate portion of the stem of the error correc tion control key I96. The link I97 is stamped or otherwise provided at its forward end with a lug I98 extending laterally to the right of the link and is engageable by a pin or other projection l5, depending from the rock shaft I5, during zeroizin operations of the shaft I5 while the key I95 is in its active or set position of Fig. 2G, to release the key I96 for return to its elevated position of Fig. 18.

Adjacent its upper end, the stemv of the error correction control key I96 is provided with a rearwardly ext-ending shoulder I99 adapted to cooperate with a stationary cross shaft 290, and to be held in yieldable engagement therewith when the key I96 is depressed and moved rearwardly to its active or set position of Fig. by a spring 29E connected between a cross shaft 202 and the lower end of the stem of the key I9fi. Adjacent the lower end of the stem of the key I99 is pivotally connected the forward end of a lever 293 rotatably mounted at its rear end on a cross shaft 294. A third arm of the lever 293 is provided with a notched portion 295 for cooperation with the cross shaft 292 to limit vertical movements of the lever 203 and the error correction control key I96. The lever is also provided with a laterally projecting portion 296 overlying the forward end of the latch lever I82. v

When moved from its elevated position of Fig. 18 to its active or set position of Fig. 20, the error correction control key I99 may be moved slightly rearward where it will be retained by the spring 29I holding the shoulder I99in frictional contact with the shaft 299. During the rearward movemerit of the key I96 as just described, the spring I98 moves the link I97 rearwardly to bring the lug I 98' into, and yieldably hold it in, its position for engagement by the pin I5 during any zero izing operations of the shaft i5 which may occur while the key I95 is in its active or set position. Movement f the error correction control key I 95 to this lowered or active position results in releasing the latch lever i852, if the latter is in its active position of Fig. 19, and retains the same in its inoperative position of Fig. 29. With the error correction control key I36 in this active position, complete depression of all digital keys 25 which have been locked in partially depressed position causes immediate automatic unlocking of the entire keyboard upon complete corrective depression of the last of such mismanipulated digital keys. The above described sliding connection of the link Ifll' with the rock shaft results in automatic release of the error correction con-- trol key I6 from its active position of Fig. 20 and return thereof to its normal or inoperative position of Fig. 18 by the spring ZIII whenever the cancelling crank II is operated to rotate shaft I5 in the manner previously described to cause zeroizing of the accumulator.

During the zeroizing operation the shaft I5 is rotated in a counter-clockwise direction as seen in Fig. 29 which causes the pin I5 to engage the lug I98 and thereby to operate the link I91. During the operation of the link I91 by the pin I5, the link I91 depresses the error correction con trol key I99 very slightly below its position of Fig. 20, which is sufficient to relieve the upward. pressure of shoulder I953 against rod 20s as maintained by spring 29! when key I9? is in its active position of Fig. 20, and the pin I5 moves the link I91 forwardly suihciently to cause spring I99 to swing the key I96 in a clockwise direction to clear the shoulder I99 from the rod 290. The spring 29I thereafter elevates the key I96 to its initial position of Fig. 18, spring I98 resiliently maintaining shoulder I99 out of the path of rod 2&9 during return movement of zeroizing crank II and shaft I5. If it is desired to retain the key I96 in its set or active position of Fig. 29 during and after a zeroizing operation, the operator manually holds the key in its set or active position, and the spring I98 cooperates with the slidable connections at the opposite ends of the link I9I to permit the necessary relative movement between the link and the key I96 and shaft and thereafter to return the link to the position of Fig. 20 where, unless the key His is so held, it may be automatically returned to its initial or elevated position during the next zeroizing operation, as already described.

The yieldable connection previously described between the column actuator 25 and the auxiliary key lock lever 85, comprising the spring I59, is provided for the purpose of preventing injury to the actuating mechanism. and associated parts if an inexperienced operator attempts to forcibly return a partially depressed digital key 25 to a normal position by raising the same without completing a full depression thereof. With this arrangement, an upward forcing of a key stem 2'! of a key which has been partially depressed will merely cause forced disengagement thereof from the associated tooth I52 on the key lock lever 85 against the action of the spring 159.

From the foregoing description of the instant embodiment of the present invention, the necessity of providing error control mechanism operable differently during different types of calculation to obviate and correct mismanipulation due to partial depression of ordinal keys in the manner best suited to the particular method of machine calculation being employed will now be understood more easily. As has been noted, in the performance of addition, for example, in this type of machine it is preferred to employ the touch method to attain the greatest degree of speed and accuracy, in which method only the lower half of the keyboard is used. The keys are individually operated, one at a time, and where the digital value in any particular order exceeds five, the operator either depresses a plurality of keys in that order, the added values of which total the number exceeding five, or he depresses one key representing a whole fraction of the number exceeding five, a proper number of times to total that number exceeding five. Hence, the operator in addition is frequently called upon to resort mentally to simple factoring and to keep in mind a definite number of strokes necessary in one or more orders to add into each such order a single ordinal number. Consequently, in rapid operation where, for example, eight is to be added in a particular order, the operator might hit the 4 key and partially depress it, counting that as one stroke. Upon learning of his error by finding the keyboard locked, he would again strike the 4 key completely depressing it, and methodically count that as a second stroke. Obviously, if that should happen and the keyboard were not thereafter locked, the operator would proceed with the problem in addition on the assumption that the two operations of the 4 key had resulted in the addition of eight, whereas only four would have been added. The fact that in addition the entire keyboard is looked upon completing the depression of a partially depressed key enables the operator to find his error and to be sure that he has properly corrected it before proceeding with the problem.

In multiple operation of the machine, on the other hand, such as multiplication, it is important that the keyboard be automatically un locked following corrective actuation of a mismanipulated key. In multiplication the fingers are arranged to strike a plurality of keys in different denominational orders simultaneously and repeatedly, and the finger arrangement (representing the multiplicand) is maintained through out the performance of the multiplication problem, the hand or hands being shifted from. time to time one denominational order to the left and repeatedly operated in accordance with the digital and denominational value of the different figures of the multiplier. Thus in the event of partial depression of any one key, the operator, upon learning of such mismanipulation due to the locking of the keyboard, can, without changing his finger arrangement, merely completely depress the mismanipulated key to correct the error and unlock the keyboard. That, of course, can be done by resting the tips of the arranged fingers on or just above the proper keys and, While holding them in that position, utilize the finger aligned with the partially depressed key individually to complete the depression of that mismanipulated key. In the event that more than one key was mismanipulated, the same corrective action is taken, each partially depressed key being fully depressed without necessitating re-alignment of the fingers, and upon corrective actuation of all mismanipulated keys the keyboard is automatically unlocked to permit continuation of the problem without necessitating re-alignment of the fingers. If, on the other hand a separate button or key had to be operated for thereafter unlocking the keyboard, as in addition, it would be necessary for the operator to change his finger arrangement, and after operation of the separate error correction key, rearrange his fingers to continue the problem.

In conjunction with the above-described operation of the instant mechanism, either in individual or in simultaneous and repetitive depression of the ordinal keys, the key lock lever 36, its actuating lever I53, and associated parts function to releasably latch any depressed key to its column actuator throughout the active phase of each complete operation of the key, so that upon partial depression and release of any ordinal key, the resulting operation of the previously described error locking mechanism will result in the partially depressed key or keys being retained in such partially depressed position to give a distinct visual indication of which keys require corrective actuation.

The above described novel error preventing mechanism is so arranged that it will necessitate the desired sequence of operations for correcting mismanipulation of the machine. More specifically, when the error correction control key I96 has been depressed prior to operation of the digital keys 25 to condition the machine for multiplication and division, the machine will again be properly conditioned for normal operation following partial depression of one or more of the digital keys 25 only if all of such partially depressed keys have been correctively actuated by fully depressing the same. This is true because of the fact that any one of such partially depressed keys, so long as it remains in partially depressed position, will prevent return of the bail H4 to normal position following complete depression of all of the other digital keys which may have been partially depressed at the same time. Such is the case because return of the error control mechanism in a manner herein described upon complete depression of one partially depressed key will not effectuate release of the latch I21 from the bail I M in any other denominational order in which a digital key has been partially depressed. Likewise, when the error correction control key 196 is in normal or raised position so that the machine is conditioned for additive or subtractive operation, all of those digital keys 25 which have been partially depressed must be correctively actuated and the error release key I86 depressed (or the canceling crank ll operated) before the machine will again be properly conditioned for normal operation. Partial depression of two keys simultaneously with the machine so conditioned for addition and subtraction and subsequent corrective actuation of only one of the said partially depressed digital keys followed by actuation of the error release key I86 will not function to release the key board for normal operation. Expressed differently, operation of the error release key I86 must be performed in its proper sequence in order to recon- 

